Polarization Conversion Systems (PCS) are efficient at producing polarized light from unpolarized sources such as LEDs for portable projectors. Conventional LCD projectors are limited by the use of absorbing polarizers that limit their energy efficieny to < 40%. PCS solves this problem by combining the properties of PGs and MTRs. A PCS has three main components: a) micro lenses, b) polarizing beam splitters, and c) patterned waveplates (figure). Using high quality PGs as thin film polarizing beam splitters, and patterned waveplates using MTRs, we have been able to engineer new PCS elements that outperform conventional designs in performance, cost, and size. The figure to the right shows the operating principle. The lens arrays in combination with the PG convert the unpolarized input into orthogonally circularly polarized spots at the focal plane. These are converted to the same polarization by the Louvered-WavePlate (LWP) and recollimated by the second lens array. Due to the impressive optical performance these PCS elements are being used in a new generaton of portable projectors (ImagineOptix).